Association between early-life exposure to mercury and cardiometabolic risk factors development in adolescence

Early-life mercury (Hg) exposure has been associated with adverse cardiometabolic health effects, though the evidence remains inconclusive. This study aims to evaluate the association between prenatal and postnatal Hg exposure and cardiometabolic risk factors in 15-year-old adolescents, considering the influence of sex, fish consumption, omega-3 polyunsaturated fatty acids (n-3 PUFAs) intake, and an obesity-related polygenic risk score (PRS).

Participants comprised 243 mother-adolescent pairs from the Spanish INMA (Childhood and Environment) cohorts. Total Hg (THg) levels were analyzed at birth and ages 4, 9, and 15 years in different matrices (cord blood, blood, and hair). At age 15, waist-to-height ratio (WHtR), fat mass percentage (%FM), systolic and diastolic blood pressure (SBP, DBP), serum alanine aminotransferase (ALT), and cardiometabolic risk (CMR) score were assessed. Sociodemographic, lifestyle, and genetic data were collected. Associations between THg levels and outcomes were analyzed using multivariable linear regression, with interaction terms to assess effect modification.

Cord blood THg was marginally and directly associated with SBP (β [95 %CI: 0.08 [-0.01, 0.17]), with stronger associations observed among boys. THg at age 9 was marginally and inversely associated with %FM and CMR score (-0.15 [-0.32, 0.01] and -0.45 [-0.95, 0.06], respectively). A U-shape association was found between blood THg at age 15 and SBP z-scores, with a cut-off at 2.8 (95 %CI: 1.28, 4.06) μg/L. Sex and the amount of fish and n-3 PUFA consumed influenced this association in an outcome-dependent manner. No other associations were detected with the other CMR outcomes evaluated.

The results of this longitudinal study suggest that both pre- and postnatal THg exposure have a relationship on SBP in adolescents. Sex appears to modify these associations.